A New Material and Structures for Light-Emitting Thyristor Applications

We have demonstrated that GaInP materials with GaP and distributed Bragg reflector (DBR) structures can be applied in light-emitting thyristors (LEThs) and depleted optical thyristors (DOTs). The GaP epitaxial film greatly improved the current spreading, so that the brightness of LEThs was also greatly improved. The luminous intensity increased by 70% at an injection current of 250 mA with the GaP epitaxial film, compared to the LEThs without a GaP film. Moreover, the DBR structure played a role to prevent the emission light from being absorbed by the opaque GaAs substrate. The DBR structure can improve the droop efficiency, reduce the operation voltage, and maintain the wavelength at high-current operation. The luminous intensity of LEThs with the 18-pairs DBR structure increased by 71% at an injection current of 900 mA, compared to LETh with only three-pairs DBR and GaP window structure. It also showed nonlinear s-shaped I - V characteristics as a function of the input light intensity. The turn-on voltages were significantly reduced, from 5.36 to 1.66 V, as the external optical input intensity changed from dark to light with 300 mW. Under certain conditions, it also showed standard diode curve characteristics; as a result, the LETh can also be used as a DOTs.